London, however, does not suddenly make Buck into an all-good, ideal, one-dimensional dog. He says that in spite of the great love which Buck has for John Thornton, Buck still retains a strong sense of the primitive. In other words, Buck's faithfulness and devotion — qualities associated with a civilized society — are apparent in his conduct toward John Thornton, but Buck still retains his protective instincts for the wild and his mastery of the primitive.
London also reminds us that Buck's body is scarred, "scored by the teeth of many dogs," so much so that other dogs would quickly acknowledge his supremacy in a fight. Buck had indeed "learned well the law of club and fang . . . he must master . . . because to show mercy was a weakness. Mercy did not exist in the primordial life . . . kill or be killed, eat or be eaten was the law." During these times, Buck relishes living with John Thornton, yet there are other, deeper claims to him also. From far deep down in the forest, he often hears wild sounds and calls that are mysteriously thrilling and compelling. He often ponders the nature of these mysterious calls, and he often thinks of running toward them, except for the fact that "the love of John Thornton drew him back to the fire again." When Thornton's partners, Hans and Pete, arrive with the long-awaited raft, Buck refuses to acknowledge them, except as friends of Thornton. He feels loyalty only to Thornton.
At this point, London shifts his point of view from Buck to the character of John Thornton, and we discover that during their dual recuperation, Thornton develops a great admiration for Buck. One day, therefore, after Hans and Pete's arrival, Thornton and his friends are sitting on the edge of a chasm, into which Thornton suddenly orders Buck to jump. Evidently, Thornton does this in order to demonstrate to Hans and Pete that Buck is totally devoted to him. In London's words, "The next instant he [Thorton] was grappling with Buck on the extreme edge."
